If it is an automatic it can go into limp mode. The M & S lights come on on the dashboard and the 'D' on the dasboard flashes. It will also only allow 3rd gear, N or R. I would suggest doing a search (if this is what you are getting) for XYZ switch and you will learn, as I have, more than you will ever need to know! Basically it is an electronic rather than mechanical issue but the switch is £400 from an LR dealer.